Field Connections; Space Temperature (Spt) Sensors; Indoor Air Quality (Co 2 ) Sensor - Carrier 48HC Installation Instructions Manual

Field Connections

Field connections for accessory sensors and input devices
are made the RTU Open, at plugs J1, J2, J4, J5, J11 and
J20. All field control wiring that connects to the RTU
Open must be routed through the raceway built into the
corner post as shown in Fig. 36. The raceway provides the
UL required clearance between high- - and low- - voltage
wiring. Pass the control wires through the hole provided in
the corner post, then feed the wires thorough the raceway
to the RTU Open. Connect to the wires to the removable
Phoenix connectors and then reconnect the connectors to
the board.
Space Temperature (SPT) Sensors —
There are two types of SPT sensors available from Carrier,
resistive input non-communicating (T55, T56, and T59)
and Rnet communicating (SPS, SPPL, SPP, and SPPF)
sensors. Each type has a variety of options consisting of:
timed override button, set point adjustment, a LCD
screen, and communication tie in. Space temperature can
be also be written to from a building network or zoning
system. However, it is still recommended that return air
duct sensor be installed to allow stand-alone operation for
back-up. Refer to the configuration section for details on
controller configurations associated with space sensors.
S 33ZCT55SPT, space temperature sensor with override
button (T- - 55)
S 33ZCT56SPT, space temperature sensor with override
button and setpoint adjustment (T- - 56)
S 33ZCT59SPT, space temperature sensor with LCD
(liquid crystal display) screen, override button, and
setpoint adjustment (T- - 59)
Use 20 gauge wire to connect the sensor to the controller.
The wire is suitable for distances of up to 500 ft. Use a
three- - conductor shielded cable for the sensor and setpoint
adjustment connections. If the setpoint adjustment
(slidebar) is not required, then an unshielded, 18 or 20
gauge, two- - conductor, twisted pair cable may be used.
Connect T- - 55: See Fig. 51 for typical T- - 55 internal
connections. Connect the T- - 55 SEN terminals to RTU
Open J20- - 1 and J20- - 2. See Fig. 71.
SEN
SEN
Fig. 71 - - RTU Open T- - 55 Sensor Connections
Connect T- - 56: See Fig. 53 for T- - 56 internal connections.
Install a jumper between SEN and SET terminals as
illustrated. Connect T- - 56 terminals to RTU Open J20- - 1,
J20- - 2 and J20- - 3 per Fig. 72.
J20-1
J20-2
C08460
SEN
SEN
Jumper
SET
SET
Fig. 72 - - RTU Open T- - 56 Sensor Connections
Connect T- - 59: The T- - 59 space sensor requires a
separate, isolated power supply of 24 VAC. See Fig. 73
for internal connections at the T- - 59. Connect the SEN
terminal (BLU) to RTU Open J20- - 1. Connect the COM
terminal (BRN) to J20- - 2. Connect the SET terminal (STO
or BLK) to J20- - 3.
BLK (STO)
BRN (COM)
BLU (SPT)
OR SET SEN
OPB COM- PWR+
NOTE: Must use a separate isolated transformer.
Fig. 73 - - Space Temperature Sensor Typical Wiring
(33ZCT59SPT)
Indoor Air Quality (CO ) Sensor —
2
The indoor air quality sensor accessory monitors space
carbon dioxide (CO ) levels. This information is used to
2
monitor IAQ levels. Several types of sensors are available,
for wall mounting in the space or in return duct, with and
without LCD display, and in combination with space
temperature sensors. Sensors use infrared technology to
measure the levels of CO
2
The CO sensors are all factory set for a range of 0 to
2
2000 ppm and a linear mA output of 4 to 20. Refer to the
instructions supplied with the CO
requirements and terminal locations. See Fig. 56 for
typical CO sensor wiring schematic.
2
To accurately monitor the quality of the air in the
conditioned air space, locate the sensor near a return- - air
grille (if present) so it senses the concentration of CO
leaving the space. The sensor should be mounted in a
location to avoid direct breath contact.
42
J20-1
J20-2
J20-3
C08461
J20-3
SENSOR
J20-2
WIRING
J20-1
POWER
WIRING
24 VAC
C10291
present in the space air.
sensor for electrical
2
2